1. Field of the Invention
This invention relates generally to solutions for moving people or items from one location to a higher or lower location along a variable slope without the need for complex leveling mechanisms. More particularly, the invention is directed toward outdoor transportation devices for moving people and things between elevated lake lots and the waterline in a safe and efficient manner along an incline that may vary substantially in slope.
2. Description of Related Art
Water-level lake lots are available for purchase with increasing rarity, and at increasingly inflated prices, substantially reducing the affordability of lake lot vacation or residential homes for all but the wealthy. At the same time, the vast majority of property bordering lakes is undeveloped and has heretofore in many cases been deemed undesirable or even undevelopable because of the grade or obstacles present between the waterline and a suitable location for building a house: The difficulties associated with getting to the focal point of such lots—the water—typically prevent the lot from being maximized as a leisure area, or from ever being useable at all for persons with special needs.
Numerous solutions have been advanced to address this problem, none of which are entirely acceptable. Such solutions range from the traditional winding stairs, which can be exhausting or even dangerous for the elderly, infants, and those with special needs, to typically traction cable-lift transport designs. Even these mechanical transports are limited in their application, being by their nature confined to either of two models: (1) a constant slope incline model, or (2) mechanically leveled models that involve moving linkages and machinery to maintain the surface of a transport platform at a relatively level position. In addition to these limitations, the inventor believes these solutions have not obtained the greatest degree of safety that potentially may be developed from alternative solutions such as the invention taught herein.
With the exception of stairs, the most commonly used transportation device in the art of elevated lake lot traversing is the cable-driven hoist platform. Such hoist platforms are exemplified by U.S. Pat. No. 3,168,937 to Redford, et al, which, although here applied to an indoor application, discloses a slope-moving meat cutting platform. Redford employs a constant slope dual rail design having a platform cantilevered between a wheel residing beneath the rail and another wheel disposed above the downward portion of the rail. Additionally, as the slope of the rails is not dependent upon any external factors, Redford shows a constant slope for the rails and includes no leveling mechanism; the teaching of Redford is therefore limited to extremely narrow applications. Redford's device is cable driven and therefore subject to heightened maintenance and safety concerns of such cable systems.
The art has recognized that not all applications enjoy a static slope, but has grappled with the solution. For instance, devices for ascending along stairs frequently must traverse not only fixed inclines, but also cross over flattened areas where landings are interspersed in the stairway. Designs accommodating variable slopes include the Hein inventions, U.S. Pat. Nos. 5,964,159 and 5,572,930. These stair alternatives incorporate a pair of rails separated by a constant vertical gauge. Leveling is achieved by rotating wheels that lie above and below each rail in a manner that keeps the wheels vertically aligned. Other leveling solutions include elevated transports that level loads strictly by gravity, the loads being suspended from a pivotable linkage, as in U.S. Pat. No. 3,935,822 to Kaufmann. Additional solution concepts for leveling include U.S. Pat. No. 5,069,141 to Ohara, U.S. Pat. No. 4,602,567 to Hedstrom; and U.S. Pat. No. 3,774,548 to Borst, each of which to varying degrees depends upon a hanging load below the level of the rail. The typical hanging load system requires the weight to be centered on the platform; otherwise, the stability and consistency of leveling will be suspect. These systems are subject to undesirable swaying motion, particularly at sudden starts and stops. Additionally of note are solutions for horizontal leveling systems that employ a complex array of tracks and multiple wheels that variously engage and disengage from their respective tracks as movement progresses, such as the “traversing elevator” described in U.S. Pat. No. 4,821,845.
Other developers have noted difficulty with obtaining reliable and consistent grip between the rails of a transport and the wheels when on a slope. The art has variously attempted to address this difficulty by use of spring loaded wheels, such as those shown in Ohara et al, U.S. Pat. No. 5,069,141, or by gripping teeth, as in U.S. Pat. No. 5,398,617, issued to Deandrea.
None of these prior art systems has maximized the potential available for reliable self leveling traversing devices. It further will be noted by those reasonably skilled in the art that the more complex the leveling, gripping, or safety system becomes, the greater the number of practical issues that arise, such as the expense of manufacture of additional components and the fact that additional components increase the potential for unacceptable failure. The present invention is capable of being practiced without such complexity, though if desired the invention can be practiced in complex embodiments while still maintaining the spirit of the invention.